Page 1162 - Basic _ Clinical Pharmacology ( PDFDrive )

1148 SECTION X Special Topics

Element [5] is the date on which the prescription was written. It The directions for use (element [11]) must be both drug-specific
should be near the top of the prescription form or at the beginning and patient-specific. The simpler the directions, the better; and the
(left margin) of the chart order. Since the order has legal signifi- fewer the number of doses (and drugs) per day, the better. Patient
cance and usually has some temporal relationship to the date of noncompliance (also known as nonadherence, failure to adhere to
the patient-prescriber interview, a pharmacist should refuse to fill the drug regimen) is a major cause of treatment failure. To help
a prescription without verification by telephone if too much time patients remember to take their medications, prescribers often give
has elapsed since its writing. an instruction that medications be taken at or around mealtimes
Elements [6] and [7] identify the patient by name and address. and at bedtime. However, it is important to inquire about the
The patient’s name and full address should be clearly spelled out. patient’s eating habits and other lifestyle patterns, because many
The body of the prescription contains the elements [8] to [11] that patients do not eat three regularly spaced meals a day.
specify the medication, the strength and quantity to be dispensed, The instructions on how and when to take medications, the
the dosage, and complete directions for use. When writing the drug duration of therapy, and the purpose of the medication must be
name (element [8]), either the brand name (proprietary name) or the explained to each patient both by the prescriber and by the phar-
generic name (nonproprietary name) may be used. Reasons for using macist. (Neither should assume that the other will do it.) Further-
one or the other are discussed below. The strength of the medication more, the drug name, the purpose for which it is given, and the
[9] should be written in metric units. However, the prescriber should duration of therapy should be written on each label so that the
be familiar with both systems now in use: metric and apothecary. For drug may be identified easily in case of overdose. An instruction to
practical purposes, the following approximate conversions are useful: “take as directed” may save the time it takes to write the orders out
but often leads to noncompliance, patient confusion, and medi-
1 grain (gr) = 0.065 grams (g), often rounded to
60 milligrams (mg) cation error. The directions for use must be clear and concise to
15 gr = 1 g prevent toxicity and to obtain the greatest benefits from therapy.
Although directions for use are no longer written in Latin,
1 ounce (oz) by volume = 30 milliliters (mL) many Latin apothecary abbreviations (and some others included
1 teaspoonful (tsp) = 5 mL below) are still in use. Knowledge of these abbreviations is essential
1 tablespoonful (tbsp) = 15 mL for the dispensing pharmacist and often useful for the prescriber.
1 quart (qt) = 1000 mL Some of the abbreviations still used are listed in Table 65–1.
Note: It is always safer to write out the direction without
1 minim = 1 drop (gtt) abbreviating.
20 drops = 1 mL Elements [12] to [14] of the prescription include refill infor-
2.2 pounds (lb) = 1 kilogram (kg) mation, waiver of the requirement for childproof containers,
The strength of a solution is usually expressed as the quantity and additional labeling instructions (eg, warnings such as “may
of solute in sufficient solvent to make 100 mL; for instance, 20% cause drowsiness,” “do not drink alcohol”). Pharmacists put the
potassium chloride solution is 20 grams of KCl per deciliter (g/dL) name of the medication on the label unless directed otherwise by
of final solution. Both the concentration and the volume should the prescriber, and some medications have the name of the drug
be explicitly written out. stamped or imprinted on the tablet or capsule. Pharmacists must
The quantity of medication prescribed should reflect the antici- place the expiration date for the drug on the label. If the patient
pated duration of therapy, the cost, the need for continued contact or prescriber does not request waiver of childproof containers,
with the clinic or physician, the potential for abuse, and the poten- the pharmacist or dispenser must place the medication in such a
tial for toxicity or overdose. Consideration should be given also to container. Pharmacists may not refill a prescription medication
the standard sizes in which the product is available and whether this without authorization from the prescriber. Prescribers may grant
is the initial prescription of the drug or a repeat prescription or refill. authorization to renew prescriptions at the time of writing the
If 10 days of therapy are required to effectively cure a streptococcal prescription or over the telephone or electronically. Elements
infection, an appropriate quantity for the full course should be pre- [15] to [17] are the prescriber’s signature and other identifica-
scribed. Birth control pills are often prescribed for 1 year or until the tion data such as National Provider Identification (NPI), Drug
next examination is due; however, some patients may not be able Enforcement Administration (DEA) number, or State License
to afford a year’s supply at one time; therefore, a 3-month supply number.
might be ordered, with refill instructions to renew three times or
for 1 year (element [12]). Some third-party (insurance) plans limit
the amount of medicine that can be dispensed—often to only one PRESCRIBING ERRORS
month’s supply. Finally, when first prescribing medications that are
to be used for the treatment of a chronic disease, the initial quan- Unfortunately, prescribing errors are common. Several groups
tity should be small, with refills for larger quantities. The purpose provide online information regarding practices designed to reduce
of beginning treatment with a small quantity of drug is to reduce or document such errors, eg, Institute for Safe Medication Prac-
the cost if the patient cannot tolerate it. Once it is determined tices (ISMP; http://www.ismp.org/) and National Coordinating
that intolerance is not a problem, a larger quantity purchased less Council for Medication Error Reporting and Prevention Program
frequently is sometimes less expensive. (MERP; http://www.nccmerp.org/about-medication-errors).